In the case where a recorded image is formed by applying an ink containing coloring particles such as a pigment to a recording medium, if the coloring particles are finely pulverized particles, light scattering on the recording medium caused by the coloring particles can be suppressed. Therefore, the image density of the recorded image can be favorably increased along with an increase in the content of the coloring particles in an ink solution. Furthermore, fine coloring particles are easily densely filled into pores that are present in the fiber and ink receiving layer of the recording medium and have a physical interaction with the pores. Thus, the recorded image has good scratch resistance.
There has been, as means for pulverizing coloring particles, a mechanical method that uses a dispersing machine such as a sand mill, a roll mill, or a ball mill (refer to PTLs 1 and 2).